The internodea and ramuli are always obtuse at the extremity and acute at 

 base, but they vary in shape from linear-clavate to obovate, the former being 

 the prevalent form of the older, the latter of the younger internodes. The 

 concejjtacles occur, several often together, on the younger lateral or terminal 

 ramuli ; they are prominent, but depressed or umbilicate in the centre, and 

 contain a placenta, suspended in the midst of a large cavity, and emitting 

 to all sides slightly branched, moniliform spore-threads. The structure of 

 the frond varies with age ; in the younger parts the filaments of the medul- 

 lary layer are few and distant, in the older they are very dense, and in the 

 oldest parts closely intertwined. The colour is a full dark blood-red, becom- 

 ing darker in drying. The substance is soft, and somewhat juicy, and the 

 frond adheres closely to paper in drying. 



The genus Erytliroclonimn is allied on tlie one side to BJiab- 

 donia and on the other to Areschoiiyia. From the first it differs 

 by having a central or axile filament, and from the latter in 

 habit, and having more prominent conceptacles. The species 

 here figured, and to which I have given the name of the proposer 

 of the genus, greatly resembles in aspect the ^. Muelleri, one of 

 the original species described by Sonder. It differs chiefly in 

 the stem, vi'hich is here quite smooth and even, while in E. 

 Muelleri it is rough, with short tubercular or filiform processes. 

 The present is quite a western, and E. Muelleri a south-eastern 

 form. Our plant is less densely branched, more rigid, and less 

 gelatinous, and more deeply coloured than E. Muelleri, and is 

 usually larger or more robust; but at Georgetown, Tasmania, 

 E. Muelleri grows to a greatly larger size, through which, how- 

 ever, it preserves its peculiar characters. I am therefore dis- 

 posed to consider these two plants as truly distinct, though 

 nearly allied to each other. 



Fig. 1. Erythroclonium Sonderi, — the natural size. 3. Branchlets with 

 conceptacles. 3. Section of a conceptacle. 4. S])ore-string from the same. 

 5. Cross section of a branch. 6. Longitudinal semi-section of the same: 

 — the latter figures variously magnified. 



